Paper is easy to take for granted, especially in the modern world, where digital is the priority. Printing on paper is even more so because there isn’t much to do with paper and ink these days. Legal and business documents provide a physical record, but not everyone works in a related field. When you go to print, depending on where you are, you might encounter a conundrum. The standard US letter size is 8.5 x 11 inches, but outside the country, everyone follows different standards. International paper sizes are different.
Paper standards are managed by different authorities across borders. In the United States, the American National Standards Institute (ANSI) regulates paper size, while the International Organization for Standardization (ISO) regulates paper size in most European countries. Japan also has its own standard, provided by the Japan Industrial Standards Committee (JISC). America uses the imperial system of measurement, while the rest of the modern world uses the metric system.
International paper sizes are designed to scale mathematically. Each new size is exactly half of the previous one. This nifty half-rule makes scaling documents easier. Standard sizes are labeled A0 to A10, with the most common being A4. But the A4 size measures 210 millimeters by 297 millimeters or, according to our measurements, 8.27 inches by 11.69 inches. US sizes are arbitrary and, for the most part, show no discernible pattern between them. The most common is Letter size measuring 8.5 inches by 11 inches (220 millimeters by 280 millimeters), the equivalent of A4, although slightly larger. Other common US sizes are Legal (8.5 inches by 14 inches) and Tabloid-Ledger (11 inches by 17 inches).
US sizes tend to run larger side by side, but not always
With the exception of the American Ledger-Tabloid size compared to the international A3 size, most comparable paper sizes are slightly larger in America. This is probably because the measurements are in inches rather than millimeters. But for international sizes, this mainly concerns the √2 ratio, the design principle that ensures that each additional size is half the previous one. The B series follows the same idea, with an aspect ratio of 1:√2.
These dimensions play an important role in printing and creating documents, depending on the standards used. Trying to print a US document, created in the Letter variety, on A3 sized paper will cause some complications. Some content may be cut off, the spacing may look weird, and the margins will not be the same, if they are respected at all. This would be relevant when working with international colleagues or peers, and vice versa. If they send you a digital document to print, you may run into formatting issues if you don’t make the proper adjustments. These discrepancies could create commercial, legal, academic or even just personal complications.
It may seem strange that the US market uses its own size, especially when the rest of the world follows different standards, but remember that the US print market is huge. The U.S. commercial printing market alone continues to grow year over year and is expected to reach $169.49 billion in revenue by 2033, according to market research.
The rest of the world uses ISO 216 and has a different history
The main reason for the dimensional changes, besides the general design, is that America uses the Imperial measurement system, while the rest of the world has adopted the metric system. But the American dimension recalls its industrial history. The standard “Letter” size is believed to come from ancient papermaking processes, influenced by the size of the molds used to create the paper itself. The standards were first adopted in the 1920s and then codified in the 1980s. Yet America has always followed the ANSI standard, even before it existed, although the origins of American paper standards are less well known.
At the same time, global standards have a different history, resulting in ISO 216 (A series), with sizes A0 to A10 used today. Its origins date back to the 18th century and a German scientist named Georg Christoph Lichtenberg, who wrote and advocated basing paper dimensions on the √2 ratio. The idea caught on in the 20th century and was officially adopted by Germany in 1922 as DIN 476, which served as the basis for today’s ISO 216 standard. The A-Series is intended to provide a unified, scalable, streamlined system that can be easily modified without requiring adherence to arbitrary dimensions – this is almost the opposite of the US system, which tends to be confusing to the rest of the world.
The good news is that US printers generally support A-series dimensions, allowing you to use both paper sizes. This is true for many small printers you can buy in 2026, all the way up to the most reliable printer brand named by Consumer Reports.
